Well here's my best guess under such a scenario:
Electoral CollegeSelelius/Henry 371
Snowe/Lingle 167
Popular VoteSelelius/Henry 46.2%
Snowe/Lingle 44.5%
Others 9.3%
The GOP's decision to pick a moderate pro-choice Republican helps them become more competitive in the North East and Mid-Atlantic, but it also destroys their stranglehold on the South. Although several right wing third party candidates run on minor party tickets and as independents; they all split each other's both and they cyphon off critical votes from the Snowe/Lingle ticket. The election is much closer than the electoral vote count indicates (I realize that the actual EVC will differ once redistricting occurs in 2010), because several large states that usually aren't competitive like California and Texas are extremely close. In fact, rather than the typical situation where only a handful of states are competitive, in this election at least 35 states are competitive, and many aren't called for much of the evening. But in the end, the various third party candidates become the achilles heel of the Snowe/Lingle ticket.